1. Field of the Invention
The present invention relates to an optical fiber cable retention system for use in joining or terminating optical fiber cables. In particular, the present invention relates to an optical fiber cable retention system for use in joining or terminating optical fiber cables having as a central core at least one optical fiber with said central core being surrounded by a flexible strength member,
which cable retention system comprises:
a pair of tapered and mating engagement components comprising:
a male engagement component having a central cavity sized to accommodate the diameter of said optical fiber cable, and having in at least one dimension a thickened first end at least a portion of which is rounded, and a body member at least a portion of which tapers in thickness away from said first end to an opposite end thereof, with a groove in the outer surface of said body member at some point along its length, and
a female engagement component having substantially uniform outer dimension, and a central cavity sized to accommodate said male engagement component therein,
and defining an engagement zone therebetween within which a portion of the flexible strength member of an optical fiber cable may be held in compressive engagement; and,
a band of elastomeric material of suitable dimension to reside in the groove in the outer surface of said male engagement component.
The present invention is intended for use in a method for retaining an optical fiber cable in joining or terminating said cable, wherein said cable comprises a central core containing at least one optical fiber surrounded by a flexible strength member,
wherein the method comprises:
providing a pair of tapered and mating engagement components comprising:
a male engagement component having a central cavity sized to accommodate the diameter of said optical fiber cable, and having in at least one dimension a thickened first end at least a portion of which is rounded, and a body member at least a portion of which tapers in thickness away from said first end to an opposite end thereof, with a groove in the outer surface of said body member at some point along its length, and
a female engagement component having substantially uniform outer dimension, and a central cavity sized to accommodate said male engagement component therein,
and defining an engagement zone therebetween within which a portion of the flexible strength member of an optical fiber cable may be held in compressive engagement;
passing the optical fiber cable through the central cavities of said engagement components;
separating a portion of the flexible strength member of said optical fiber cable from the central core of said at least one optical fiber and wrapping said portion of said flexible strength member back over the rounded, thicker end of said male engagement component, and back along the tapering portion of said body member of said male engagement component;
placing an elastomeric band of diameter suitable to reside in the groove of said male engagement component over the wrapped portion of said strength member and affixing said strength member to said male engagement component by positioning said elastomeric band over said strength member within the groove in the outer surface of said male engagement component; and,
engaging said female engagement component in compressive mating engagement with said male engagement component, with the wrapped portion of said flexible strength member compressively engaged therebetween.
2. Description of the Related Art
Optical fiber cables have been used in communication for some time and have proven to have advantages over electrical systems. However, optical fiber cables contain delicate fibers which must be spliced together or connector-ized to join cables or terminate them.
These cables are typically provided with some kind of protective sheath in the form of a strength member surrounding a central core of optical fibers. Various prior art references have proposed splice housings and connectors for joining and terminating optical fiber cables, and specifically for holding the strength member in tension to prevent the cable from pulling away and placing stress on the optical fibers. Because of the fragile nature of the optical fibers, crimping, clamping, and other mechanical methods employed with electrical conductors cannot be employed.
U.S. Pat. No. 4,190,316 to Malsby, Doty and Patel shows a Lens Connector for Optical Fibers. This device is a connector for optical fibers in which two optical fibers are held in a light-transmissive relationship across a lens member. The fibers are held in place, at least in part, by male and female engagement members held within the connector backshell which engage the strength member of the optical fiber cable. The reference shows a special tool used to spread the strength member and wrap it back over the male engagement member. In practice, however, the strength member was not held in position properly to be engaged by the female engagement member and the grip on the strength member was not properly secured. When this occurred, cable strength would not be retained, and the optical fibers could break, causing the connector to fail in service.
U.S. Pat. No. 4,744,622 to Cherry and Werner shows an Optical Fiber Splice Case for joining composite cables in a tube surrounded by wire strands. The device grips the wire strands within elongated jaws which collectively form a cylindrical member which is compressed down around the wire strands to withstand tensile forces. In practice, such a device can only resist high tensile forces by clamping the optical fiber cable more securely, increasing the risk of damage to the optical fibers themselves.
U.S. Pat. No. SIR H00595 to Lafaw shows a Field Splice Assembly for Tactical Fiber Optic Cable. This device shows a two piece enclosure with a central groove to hold two optical fiber cables and a central cavity wherein the optical fibers may be joined. In this device, the optical fiber cables are held in place by the clamping action of the splice housing, permitting resistance to tensile forces only by risking damage to the optical fibers.
U.S. Pat. No. 4,974,925 to Troutman, Opdahl and Gee shows a Splice Casing Assembly in which an internal strength member is separated from the optical fibers and clamped separately. While this device avoids crimping or clamping of the optical fibers themselves, the tensile forces are still directed at disengaging the connection.